The purpose of this project is to study the effect of pesticides on ion transport across lipid bilayer membranes by studying the electrical properties of the membranes. Any changes in the membrane electrical properties induced by the presence of pesticides will offer some clues to the understanding of the transport mechnanisms at the molecular level. Three aspects are being considered: (1) the interaction of pesticides with "continuous" lipid membranes involving partition-diffusion processes, (2) the interaction of pesticides with "porous" lipid membranes and (3) the mechanisms controlling ionic channels in excitable membranes in the presence of pesticides. Information on the effect of pesticides on membrane transport is obtained from DC, AC and transient current measurements. The effect of pH of the membrane bathing solution on the membrane electrical characteristics, as well as the effect of the concentration of membrane modifier and lipid content of membranes, is being studied. Electrical measurements are supplemented by spectrophotometric studies. A random walk model is being developed to simulate ion migration through membrane channels.